Photometric assessment of skin colour and lightness using a tristimulus colorimeter: reliability of inter and intra-investigator observations in healthy adult volunteers.

The ageing of injuries is an important aspect of forensic medicine, and one which can have significant medico-legal consequences. The sequence and timing of color changes associated with the appearance and disappearance of bruises, as well as the factors which govern this process, have long been a source of controversy. Whilst visual assessment currently remains the easiest and most practical method available to date bruises, it appears unlikely that it can be relied upon to provide an accurate and consistent measure of the age of a bruise. In an ongoing pilot study designed to assess the applicability of colorimetry to the dating of bruises, the Dr. Lange MICRO COLOR tristimulus colorimeter will be used to assess how the color and colour density (lightness) of bruises change over time. The results of a preliminary study are presented, in which the variability of skin colour measurements obtained by different investigators was assessed. Measurements were taken of the same area on the volar surface of the forearm of five volunteers, after having them remain with their arm motionless for a predetermined period of time (2, 5, and 10 min). Four sets of measurements were taken by each investigator over a total period of 3 h. No significant statistical difference was found after the resting time interval of 5 min between the values obtained by the two investigators (P > 0.05). While studies on a much larger population remain to be completed, our initial findings would seem to suggest that the colorimeter is able to provide an objective, quantitative, and relatively consistent measure of skin colour when used by different individuals.